1. Field of the Invention
The present invention relates to a flash memory device with a nanoscale floating gate and a method of manufacturing thereof, and more particularly, a flash memory device with a nanoscale floating gate that utilizes self-assembled nanocrystals embedded in a polymer film.
2. Description of the Related Technology
A flash memory is produced by combining a small cell area of an erasable programmable ROM (EPROM) with the electrical erasability of an electrically erasable programmable ROM (EEPROM) to be erased and reprogrammed in blocks unlike the EEPROM so that it can be easily rewritten and work much faster.
A flash memory is used in a variety of electronic equipments such as nearly all main board BIOS chips, mobile telephones, set-top boxes, digital cameras, DVD players, MP3 players, games and the like.
Three-dimensionally confined nanocrystallines embedded in a dielectric layer have been investigated extensively for the applications in nonvolatile flash memories with nanoscale gates. Even though some studies concerning the formation of Si nanoparticles embedded in a SiO2 have been conducted using scanning prove, e-beam, and X-ray methods (S. Huang, S. Banerjee, R. T. Tung, and S. Oda, J. Appl. Phys. 94, 7261 (2003), S. J. Lee, Y. S. Shim, H. Y. Cho, D. Y. Kim, T. W. Kim, and K. L. Wang, Jpn. J. Appl. Phys. 42, 7180 (2003), S. Huang, S. Banerjee, R. T. Tung, and S. Oda, J. Appl. Phys. 93, 576 (2003)), a study of self-assembled nanoparticles embedded in an alternative insulation layer by using simple techniques has not been performed yet.
Demand for replacing SiO2, which has been mainly used as a dielectric layer in present, with novel materials is increased. Polyimide as an organic dielectric insulation material is developed to replace conventional inorganic dielectric insulation materials. Since polyimide exhibits characteristics of thermal, mechanical, inherent properties, it has been widely used in a variety of ultra-precision electronic industries including insulating intermediate layers of integrated circuits, high density interconnecting packages. Particularly, it is noted that a dielectric constant of polyimide is lower than that of the conventional inorganic material.
The flash memory device generally comprises a thin tunnel oxide on the silicon substrate, a floating gate composed of polysilicons thereon, an insulation layer between gate electrodes formed on the floating gate electrode, and a control gate electrode permitted for an appropriate voltage.
The drawback of conventional tunnel oxide is that it requires a complex manufacturing process and high programming voltage.